RVP is upgraded to 11.4 SP4 and once the RayVentoryPortalScheduler service is started, the schedule.xml file from the previous RVP build has its contents deleted.
RVP 11.4 SP4 introduces a new OS filter target option which isn't added to an existing schedule.xml file, which unfortunately causes the RayVentoryPortalScheduler service to treat it as corrupt and fails to retain its contents.
1) Stop the RayVentoryPortalScheduler service.
2) Restore the backed up legacy schedule.xml file.
3) Search that file for all instances of OSFilterTargetDefinition to see if any of them look like this:
<TargetType xsi:nil="true" />
<TargetType xsi:nil="true" /> to
5) Start the scheduler service.